Nearly half of the U.S. population will meet criteria for a psychiatric disorder during their lives, and 1 in 17 has a seriously debilitating illness. Increasingly, these psychopathologies are conceptualized as the late-stage cul- mination of aberrant developmental processes shaped by a complex interplay of genes and experience, includ- ing those occurring in utero. Decades of studies with pregnant animals demonstrate that stress-elicited pertur- bations in maternal biology affect offspring development, leading to a profile characterized by heightened be- havioral and physiologic stress responsivity. Studies of distress in pregnant women, which range from exami- nations of life stress to psychiatric disorder, largely mirror these findings. Despite ample evidence linking ante- natal maternal functioning to offspring outcomes, the mechanistic pathways for this in utero influence on chil- dren's neurodevelopment remain unknown, particularly with human subjects. The burgeoning field of epigenet- ics - the detection of the molecular effects of environmental experience - has only minimally been applied to pregnant women, yet may provide a vital link in understanding the mechanisms involved in the fetal origins of psychiatric disease risk. The goal of this project is to use recent advances in studying epigenetic gene regulation to identify the biological mechanisms mediating the impact of maternal distress on perinatal development. Aim 1: Determine the influence of pregnant women's distress on epigenetic gene regula- tion relevant to perinatal development. Specifically, to establish whether (a) prenatal distress (daily life stress assessed 3x in pregnancy using 24-hour Ecological Momentary Assessment (EMA) via a Personal Digi- tal Assistant (PDA)) and mood symptoms elicited by clinician interviews) predict women's stress hormone lev- els (cortisol (from 3x, 12 salivary samples in 48-hours) and CRH (3x blood draws) and gene expression in her PBL (3x blood draws); (b) the timing and degree of women's altered stress hormone levels and PBL gene ex- pression predict placental gene expression; (c) these mood-dependent biological alterations are associated with the epigenetic mechanism of DNA methylation. Aim 2: Determine perinatal consequences of pregnant women's distress. Specifically whether, (a) women's distress-associated altered HPA-axis hormone levels, PBL and placental gene expression/epigenetic variation, predict fetal cord blood gene expression/epigenetic variation, as well as a neurobehavioral profile characterized by heightened reactivity to novelty (fetal and new- born autonomic and central nervous system regulation in response to stimuli). Aim 3: Establish causal influ- ence of epigenetic modification on offspring neurodevelopment. Specifically, using a rodent model in which brain effects of chronic maternal prenatal stress exposure can be directly assessed, we aim to determine (a) the influence of maternal condition on DNA methylation and gene expression in maternal PBLs, placenta, and in the fetal/infant brain and, (b), the relationship between epigenetic variations in these tissues and the de- velopment of the postnatal ANS and CNS as indexed by behavioral and stress-hormone responsivity.